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clear. During cooling the liquid is frequently shaken and after standing
for 48 hours is filtered to separate the oxalates, which are washed with 3
quantities of 25 c.c. of water and are then treated with boiling potassium
hydroxide solution (100 c.c. of potassium hydroxide solution of 45 Baume
and 200 c.c. of water). In this way the oxalates are decomposed, and
after cooling the bases (aniline and p-toluidine) are separated and weighed,
the o-toluidine being then determined by difference. If the aniline is deter-
mined, as in (a), in the mixture, of bases separated from the oxalates and
dried with potash, the proportion of aniline and hence that of p-toluidine
in the oil are known.

Aniline oil for red lias I) = i-ooo'-i-oog at 15, distils almost completely
between 182 and 198 and is almost entirely soluble in dilute hydrochloric
acid. That for safranine has D ~ 1-032 - 1-034 and often contains consider-
able quantities of non-basic products, so that it gives a very turbid solution
with dilute hydrochloric acid ; it contains as a rule 4-6% and sometimes 12%
of p-toluidine.

3.   Liquid Toluidine

The determinations to be arc the same as with aniline oils. Accord-
ing to Lunge 1 the density may be used to deduce the proportions of o- and
p-toluidines, when aniline and other substances are absent.

o- and p-Toluielines are also sold in a fairly pure form. The former is a liquid,
D = 1-0037 at I5' .198 and the second solid, D = i-o.|.<>, 45,


(Tartar Emetic)
K(SbO)CJlA + pI20 = 332-3

Colourless, transparent crystals, which readily effloresce, becoming
opaque, irregular pieces or crystalline powder. It dissolves in 17 parts
of cold water with a faintly acid reaction, but is insoluble, in alcohol. It
may be impure with cream of tartar, calcium salts, sulphates, chlorides,
antimony and potassium oxalate, iron, zinc, copper, lead and arsenic. The
various tests to be made are as follows :

1.  Solubility.A clear solution should bo obtained with 0-5 gram and
8-10 c.c. of cold water or i c.c. of boiling water;  any   insoluble residue
indicates cream of tartar or calcium salts.

2.  Sulphates, Chlorides, Oxalates, Lime.4 grams are dissolved
in 80 c.c. of water acidified with tn.rtn.ric acid and four portions of the solu-
tion tested respectively with barium chloride, silver nitrate, calcium chloride
and ammonium oxalate.

3.  Arsenic.0-5 gram, dissolved in a little cone, hydrochloric acid
and treated with 5 c.c. of Bettendorf's reagent, should not colour within
an hour.

4.  Metals.i gram, dissolved in 20 c.c. of water and sodium, hydroxide
solution added until the precipitate formed redissolvcs and then saturated

1 Chem. Ind., 1885, VIII, p. 74.water may be used for 100 grams of oil.e determined by the method